The subtalar joint is a joint in the foot formed between the talus and calcaneus and it serves several important roles in human gait. For example, the subtalar joint allows for inversion and eversion of the rear portion of the foot about the lengthwise axis of the foot and abduction and adduction relative to the vertical axis of the tibia. In addition, the subtalar joint allows both pronation and supination to occur and serves to translate rotation of the foot to the tibia and vice versa. The subtalar joint is composed of three articulating facets between the talus and the calcaneus: the anterior, middle, and posterior facets. The anterior and middle facets produce a gliding motion whereas the posterior facet produces a complex triaxial movement due to its saddle shape.
Commonly, inflammatory arthritis, such as rheumatoid arthritis, affects the subtalar joint and requires treatment. Rheumatoid arthritis is known to destroy the subtalar joint through synovitis and, in some cases, directly damages the cartilage in the joint or the tendons around the ankle. In addition to inflammatory arthritis, other afflictions can also affect the subtalar joint, such as eccentric forces that act on the subtalar joint and erode the joint causing pain and discomfort.
Various forms of treatment can be used to treat the afflictions that affect the subtalar joint. For example, various non-operative treatments, such as activity modification, weight-loss, prescription shoes, and/or medication can be used. Alternatively, when non-operative treatments are not successful at providing adequate treatment, operative treatments can be used, such as arthrodesis—the fusing of the talus to the calcaneus. Arthrodesis is generally accomplished by removing any remnants of cartilage from the subtalar joint and placing screws and/or bone grafts across the subtalar joint. This treatment, however, presents several disadvantages. For example, it permanently fixes the talus to the calcaneus, eliminating movement between these bones, and sometimes results in pain and discomfort requiring the performance of subsequent procedures to address these issues.
Therefore, a need exists for improved surgical implant systems, methods, and components for use in joint arthroplasty.